Variable reluctance hall effect resolver



Oct. 6, 1964 J. CARLSTEIN VARIABLE RELUCTANCE HALL. EFFECT RESOLVER Filed April 12, 1961 2 Sheets-Sheet l mmvrozc TOSEPH (HELSTE/A/ flrrallvfy Oct. 6, 1964 J. CARLSTEIN 3,152,261

VARIABLE RELUCTANCE HALL EFFECT RESOLVER Filed April 12, 1961 2 Sheets-Sheet 2 E max ,4 '4

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United States Patent O 3,152,261 VARIABLE RELUCTANCE HALL EFFECT RESOLVER Joseph Carlstein, East Meadow, N.Y., assignor to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Filed Apr. 12, 1961, Ser. No. 102,537 6 Claims. (Cl. 307-11) My invention relates to a variable reluctance Hall eifect resolver and more particularly to an improved electrical resolver which is more accurate, which is simpler in construction, and which is less expensive to manufacture than are resolvers known in the prior art.

Devices are known in the prior art for the solution of unknowns in a right triangle. These devices, or resolvers, have rotor and stator windings. Where a voltage proportional tothe hypotenuse of the right triangle is applied to the stator winding, the rotor windings produce outputs providing an indication of the sides of the triangle when the rotor shaft is positioned at an angle equal to the angle between a side and the hypotenuse.

In resolvers of the prior art of the type described above, great care must be taken in the construction of the device if output signals which are purely sinusoidal in form are to be generated. Where, as is customary, the windings are disposed in slots, the device must be compensated for reluctance errors which otherwise would result. Even where the winding turns are distributed in an attempt to avoid these errors a residual error remains. It will be appreciated that devices requiring such care in their construction are relatively expensive to manufacture. In order that resolvers of the prior art produce a sensible output, it is necessary that they be excited from a source of alternating current volt age.

I have invented a resolver which embodies an improvement over resolvers of the prior art described above. My resolver employs no windings so that its output is not affected by errors which otherwise would be introduced by variations in the reluctance of the air gap between a stator and rotor winding. My device is adapted to be excited either from an alternating current source or from a direct current source. My resolver is relatively simple in construction as compared with resolvers of the prior art and hence is less expensive to manufacture.

One object of my invention is toprovide a variable reluctance Hall eifect resolver which is more accurate than are resolvers of the prior art.

Another object of my invention is to provide a variable reluctance Hall effect resolver, the output of which requires little or no compensation for errors inherent in its construction.

A further object of my invention is to provide a variable reluctance Hall effect resolver which has no wind ings.

A still further object of my invention is to provide a variable reluctance Hall eifect resolver which is simple and less expensive to construct than are resolvers of the prior art.

Other and further objects of my invention will appear from the following, description.

In general my invention contemplates the provision of a variable reluctance Hall effect resolver in which a sinusoidally skewed rotor of magnetic material varies the flux passing through a pair of Hall crystals having their outputs connected in series opposition to produce an output signal, the value of which varies as a sinusoidal function of rotor shaft position.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGURE 1 is a sectional view of one form of my variable reluctance Hall effect resolver.

FIGURE 2 is a longitudinal sectional View of the form of my variable reluctance Hall effect resolver shown in FIGURE 1 and taken along the line 2-2 of FIGURE 1.

FIGURE 3 is a schematic view of my variable reluctance Hall effect resolver developed along a line perpendicular to the rotor axis to show the effective iron between a pair of poles of my resolver in one position of the rotor shaft.

FIGURE 4 is a diagram showing the variation in output voltage with shaft position for a form of resolver having a hemicylindrical rotor.

Referring now more particularly to FIGURES 1 and 2 of the drawings, my variable reluctance Hall eifect resolver, indicated generally by the reference character 10, includes a stator 12 provided with two pairs of diametrically oppositely extending poles M- and 16 and 1% and 2d. The poles 14, 16, 18, and 26* may be permanent magnets, as indicated in the drawings, to produce a flux indicated by the broken lines in FIGURE 1. As will be explained hereinafter, it will be appreciated that the poles 1d, 16, 1S, and 2d could as well be provided with windings energized to produce the flux I apply a respective layer 22 of a suitable semi-conductor material to the face of each of the poles 14, 16, I3, and 20. The semi-conductor material may be any suitable material such, for example, indium arsenide, indium antimonide, indium and phosphorus, and galenium and antimony. I connect a pair of respective input conductors 24 and 26 to each of the layers 22 along one axis thereof. 1 connect the conductors 24 to a conductor 28 leading to one terminal of a suitable source 36) of alternating current potential and connect the conductors 26 to a conductor 32 leading to the other terminal of the source 30. It will be seen that in this manner I apply an alternating current potential to each of the layers 22 along one axis thereof. I connect a pair of respective output conductors 34 and 36 to each of the layers 22 at points along an axis at right angles to the axis along which the conductors 24 and 26 apply the input signal.

My resolver includes a rotor shaft 38 supported in re spective bearings 40 and 42 carried by end plates 44 and 46 of the stator 12. I mount a rotor 48 formed from a suitable magnetic material on the shaft 33 for rotation therewith. From the structure thus far described it will be seen that the fiux passes through each of the layers 22 in the direction of an axis which is perpendicular to the mutually perpendicular axes along which the bars of conductors 24 and 26 and 34 and 36 are disposed. As is known in the art, when a current passes through a semiconductor in a direction of one axis which is perpendicular to the axis of flux passing through the semi-conductor, then a voltage is produced in the direction of an axis which is substantially perpendicular both to the current and flux axes. Thus under the conditions outlined above, with a current produced from the signal 30 passing through a layer 22 in the direction of an axis along which conductors 24 and 26 are disposed a voltage is generated across the conductors 34 and 36. As is also known in the art, the magnitude of this voltage is a function of the flux passing through the layer 22.

I connect the conductors 34 and 36 associated with pole 14 and the conductors 34 and 36 associated with pole 16 between a pair of output terminals 50 and 52 so that the voltage in the layer 22 on pole 14 opposes the voltage generated in the layer 22 on pole 16. I connect the conductors 34 and 36 associated with pole 18 and the conductors 34 and 36 associated with pole 20 between a pair of output conductors 54 and 56 so that the voltage gencrated in the layer 22 on pole 1S opposes the voltage generated in the layer 22 on pole 20.

For purposes of explanation, let us assume that the rotor 48 is a hemicylinder of magnetic material. Assume also that each of the poles I4, 16, I8, and 2h subtends a central angle at while the inter-pole space subtends an angle ,8, as indicated in FIGURE 1 of the drawings. It will be appreciated that, considering the phase of the voltage produced in the layer 22 on pole 14 as being positive, and the phase of the voltage generated in the layer 22 on pole 16 as being negative with the hemicylinder so arranged as to provide maximum coupling between the poles 18 and 20 and the pole I4, then the R.M.S. value of the voltage produced in the layer 22 of pole 14 will be a maximum as indicated by the portion A of the curve shown in FIGURE 4. As the rotor 48 rotates in the direction of the arrow X from the position described, it will be appreciated that the flux coupling to pole 14 will be a maximum until the rotor has rotated through an angle equal to At this point the flux coupled to the pole 14 rapidly decreases and the flux coupled to the pole 16 rapidly increases until the flux coupled to the pole 16 is a maximum. The transition between the time of maximum coupling to the pole 14 and that of maximum coupling to the pole I6 is indicated by the portion B of the curve in FIGURE 4. The time of maximum coupling tothe pole 16 is indicated by the portion 0 on the curve of FIG- URE 4. As can be seen by reference to the figure, this maximum coupling exists from the point to the point At this latter point the coupling to the pole 15 rapidly decreases while the coupling to the pole l4 rapidly increases over the portion D of the curve until the level A at the output terminals and 52 is again reached.

From the explanation given hereinabove in connection with a hemicylindrical rotor and from the curve of FIGURE 4, it can be demonstrated by a Fourier analysis that a rotor 48 sinusoidally skewed through 180 in the direction of the axis of shaft 38 Will product a sinusoidal output at the terminals 50 and 52. To avoid an extensive analysis and to demonstrate this effect, I have in FIGURE 3 shown a view of my resolver developed in a direction perpendicular to the axis of shaft 38. In the figure the lines 58 and 60 enclose the elIective area of iron coupling flux between the poles. In the position shown the maximum etfect is on the pole 14. Considering this pole and its companion pole 16, it will be seen that if the area a coupling flux to the pole 16 were subtracted from the area coupling flux to the pole 14 the shape of the iron under the pole 14 would be altered as indicated by the broken line b. Similarly if the area 0 of iron coupling flux to the pole 16 were subtracted from the area of iron acting on the pole 14, then the lower part of the curve illustrating the iron under the pole 14 would be modified as shown by the broken line d. I accomplish this subtraction operation by connecting the outputs of the layers 22 of the poles l4 and 16 in series opposition between terminals 50 and 52. Similarly another sinusoidal function will be produced at the pair of terminals 54 and 56. The output of this second set of poles I8 and 2th is 90 displaced in space from the output of the first pair.

While I have shown a source 30 of alternating current potential, it will be appreciated that I could as well provide a source of direct current potential. Alternatively, while I have shown permanent magnetic poles 14, 16, 18,

and 20, I could as well provide poles in which alternating or direct flux is produced by energized windings carried between poles.

In use of my variable reluctance Hall effect resolver, I apply a suitable voltage such as the alternating current voltage from source 30 to the current leads 24 and 26 of the layers 22 of semiconductor material. With the current leads so energized, the output terminals 50 and 52 carry a signal, the R.M.S. value of which is proportional to the angular position of the shaft 38. Similarly terminals 54 and 56 carry a signal which is displaced in space from the signal at terminals 50 and 52. As the shaft 38 rotates, the R.M.S. values of the signals at the pairs of terminals 50 and 52 and 54 and 56 varies as a sinusoidal function of shaft position.

It will be seen that I have accomplished the objects of my invention. I have provided a variable reluctance Hall effect resolver which has no windings. My resolver does not require that its output be compensated for the effect of variations in reluctance such as are present in resolvers employing windings. My resolver is more accurate than are resolvers of the prior art. It is simple in construction and is inexpensive to manufacture.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, what I claim is:

1. In a resolver a stator, semiconductor material carried by said stator, means for directing flux through said semiconductor material, means for passing a current through said semiconductor material in a direction substantially perpendicular to the direction of said flux to generate a voltage in the semiconductor material along an axis substantially perpendicular both to the direction of said current and to the direction of said flux, a hernicylindrical slug of magnetic material sinusoidally skewed in the direction of its length, means mounting said slug in the path of said flux for rotary movement sinusoidally to vary said flux as it rotates.

2. A resolver including in combination a stator providing a pair of poles, semiconductor material carried by said poles, means for directing flux through the semiconductor material carried by said poles, means for directing a current through the semiconductor material carried by said poles in a direction substantially perpendicular to the direction of said flux to generate respective voltages in said semiconductor material along axes perpendicular both to the flux and to the current passing through the poles, a hemi-cylindrical slug of magnetic material sinusoidally skewed in the direction of its length, means mounting said slug in the path of said flux for rotary movement sinusoidally to vary said flux as it rotates, a pair of output terminals and means connecting said voltages in series opposed relationship between said output terminals.

3. A resolver including in combination a stator having two pairs of opposed poles, semiconductor material carried by each of said poles, means for directing magnetic flux through the semiconductor material carried by said poles, means for passing a current through the semiconductor material carried by each of said poles to generate a voltage in the semiconductor material of each pole along an axis perpendicular both to the flux and to the axis of the current passing through the pole, a hemi-cylindrical slug of magnetic material sinusoidally skewed in the direction of its length, means mounting said slug in the path of said flux for rotary movement sinusoidally to vary said flux as it rotates, a first pair of output terminals, a second pair of output terminals,

means connecting the voltages in the semiconductor material on a first pair of said poles in series opposed relationship between the first input terminals and means for connecting the voltages in the semiconductor material on the other pair of poles in series opposed relationship between the second pair of terminals.

4. A resolver including in combination a stator having a pair of poles, semiconductor material carried by said poles, means for directing flux in the same sense through the semiconductor material of each of said poles, means for passing currents through the semiconductor material on the respective poles in a direction at right angles to the direction of said flux to generate voltages along axes perpendicular to the directions both of said flux and of said current, a hemi-cylindrical slug of magnetic material sinusoidally skewed in the direction of its length, means mounting said slug in the path of said flux for rotary movement sinusoidally to vary said flux as it rotates and means for combining said voltages in the opposite sense to produce an output signal.

5. A resolver including in combination a stator providing a pair of poles, semiconductor material carried by said poles, means for directing flux through the semiconductor material on said poles, means for passing a current through the semiconductor material on each of the poles in a direction perpendicular to the direction of the flux passing through the pole to generate a voltage along an axis perpendicular both to the flux and to the current in the semiconductor material a hemi-cylindrical slug of magnetic material sinusoidally skewed in the direction of its length, means mounting said slug in the path of said flux for rotary movement sinusoidally to vary the flux as it rotates and means for combining said voltages in the opposite sense.

6. A resolver including in combination a stator providing a pair of poles, semiconductor material carried by said poles, means for directing flux through the semiconductor material on said poles, means for passing alternating current through the semiconductor material on each of the poles in a direction perpendicular to the direction of the flux passing through the pole to generate a voltage along an axis perpendicular both to the flux and to the current in the semiconductor material a hemicylindrical slug of magnetic material sinusoidally skewed in the direction of its length, means mounting said slug in the path of said flux for rotay movement sinusoidally to vary the flux as it rotates and means for combining said voltages in the opposite sense.

References Cited in the file of this patent UNITED STATES PATENTS 2,924,633 Sichling et al. Feb. 9, 1960 3,018,395 Carlstein Jan. 23, 1962 3,028,092 Fay April 3, 1962 3,112,464 Ratajski et al. Nov. 26, 1963 

3. A RESOLVER INCLUDING IN COMBINATION A STATOR HAVING TWO PAIRS OF OPPOSED POLES, SEMICONDUCTOR MATERIAL CARRIED BY EACH OF SAID POLES, MEANS FOR DIRECTING MAGNETIC FLUX THROUGH THE SEMICONDUCTOR MATERIAL CARRIED BY SAID POLES, MEANS FOR PASSING A CURRENT THROUGH THE SEMICONDUCTOR MATERIAL CARRIED BY EACH OF SAID POLES TO GENERATE A VOLTAGE IN THE SEMICONDUCTOR MATERIAL OF EACH POLE ALONG AN AXIS PERPENDICULAR BOTH TO THE FLUX AND TO THE AXIS OF THE CURRENT PASSING THROUGH THE POLE, A HEMI-CYLINDRICAL SLUG OF MAGNETIC MATERIAL SINUSOIDALLY SKEWED IN THE DIRECTION OF ITS LENGTH, MEANS MOUNTING SAID SLUG IN THE PATH OF SAID FLUX FOR ROTARY MOVEMENT SINUSOIDALLY TO VARY SAID FLUX AS IT ROTATES, A FIRST PAIR OF OUTPUT TERMINALS, A SECOND PAIR OF OUTPUT TERMINALS, MEANS CONNECTING THE VOLTAGES IN THE SEMICONDUCTOR MATERIAL ON A FIRST PAIR OF SAID POLES IN SERIES OPPOSED RELATIONSHIP BETWEEN THE FIRST INPUT TERMINALS AND MEANS FOR CONNECTING THE VOLTAGES IN THE SEMICONDUCTOR MATERIAL ON THE OTHER PAIR OF POLES IN SERIES OPPOSED RELATIONSHIP BETWEEN THE SECOND PAIR OF TERMINALS. 